This invention relates to a developing device for an electrophotographic copier, a laser printer and the like and more particularly to a developing device composed of a developing tank and a supply tank having an improved sealing means for sealing the supply outlet of the supply tank through which developing agent drops into the developing tank.
A developing device for a copier is detachably attached near the copier's photoreceptor and is comprised of a developing tank and a supply tank having a supply outlet through which developing agent is supplied into the developing tank. Since the developing tank itself is also provided with an opening through which toner can be applied to the photoreceptor, if the copier has its developing device filled with developing agent, it is difficult to prevent the developing agent from spilling out when the copier is transported. For this reason, a copier is shipped without any developing agent at all in the developing device or by closing the supply outlet with a removable sealing material and putting developing agent only in the supply tank. Such a sealing material is removed by the user when the copier is set and is ready to be used. FIGS. 1A and 1B show a prior art sealing means 3 used for such a purpose with one end 4 extending forward from the outlet 2 of the supply tank 1. After the copier is set, the user must pull the end 4 to remove the sealing means 3 from the supply outlet 2, but the surface of the sealing means 3 is usually covered with developing agent even after it is removed from the supply tank 1. The user usually finds it difficult to keep his or her hands clean after removing the sealing means 3. Another disadvantage of such prior art sealing means is that the user may forget to remove it before beginning to use the copier.